Treatment of hydrocarbon oils



Patented July 15, 1941 Ivar H. Kinneberg, Chicago, 111., assignor to Universal Oil Products Company, Chicago, Ill., a a

corporation of Delaware Application October 31, 1938, Serial No. 238,029

No Drawing.

3 Claims.

This invention relates more particularly to the conversion of hydrocarbon fractions produced in the distillation of petroleum or other hydrocarbons generally, especially hydrocarbon oils which may be vaporized without undergoing appreciable decomposition. More specifically the invention is concerned with hydrocarbon oil conversion processes differing widely from the conventional thermal processes and involves the use of a particular and-specific type of catalyst which functions to promote the formation of low-boiling hydrocarbons particularly desirable in motor fuel, Production.

The art of pyrolytically cracking relatively heavy hydrocarbons to produce large yields of gasoline by the use of heat and pressure is very extensively developed and thevarious principles involved are embodied in numerous commercial processes. Where the use of-catalysts is involved, however, very little knowledge of a deflnite character is available for hydrocarbon reactions as well as for other catalytic processes generally. A number of catalysts are known,

such as reduced metal catalysts, particularly iron or nickel, which influence hydrocarbon conversion reactions, but the gas yields are relatively high and the gasoline yields relatively ,low.

These catalysts are readily poisoned by sulfurcompounds and are also rapidly coated with carbonaceous materials which makes them practically inert. Some oxides of metals are also known which promote dehydrogenation reactions where the. gasoline yields are low and the gases produced are undesirable for further processing. It is among the features of the catalyst described in the present invention that by its use hydrocarbon reactions are accelerated which lead to large yields per pass of high antiknock gasoline and the simultaneous production of gas of relatively high olefin content which may be further processed to produce polymer gasoline. In this type of hydrocarbon conversion reaction carried out in the presence of my catalyst the production of carbonaceous materials which deposit on the surface of the catalyst is relatively low. The catalyst is also characterized by its refractory character which enables it to maintain its catalytic properties under high temperature conditions, by the ease and simplicity 'of manufacture, and its exact reproducibility.

In one specific embodiment the present invention comprises the conversion of hydrocarbon fractions containing substantially no gasoline into material yieldsof gasoline having high antiknock value by subjecting such vapors at elevated temperatures and substantially atmospheric pressure to contact with a silica base catalyst activated by treatment with aluminum.

Although .the cracking of high-boiling hydrocarbons in the presence of my catalyst may generally .be of greater importance, hydrocarbons largely within the gasoline, boiling point range as, for example; naphtha cuts, gasoline lacking in light and/or heavy ends, cracked gasoline, etc.

may-be processed to increase their antiknock value. After contact with the catalyst the vaporous products are separated, a part or whole of the partially converted oil may be returned to further catalytic treatment, low-boiling hydrocarbons within the gasoline boiling point range are condensed and collected, and the hydrocarbon gases which are high in olefin content, particularly propene and butenes, may be subjected in part or in whole to polymerizing treatment to form additional yields of high antiknock gasoline.

In the preparation of the catalysts usedin the present process, it is preferable to disperse aluminum on a primary base or carrier prepared by precipitating silica from a solution as a gel. The most convenient and ordinary method of preparation of such a 'gel is to acidity an aqueous solution of sodium silicate by the addition of a min-- eral acid. [The excess of acid and the concentration of the solution in which the precipitation is brought about will determine the primary activity of the silica and its suitability as a support for the added aluminum to produce a composite catalyst of increased activity. Although various methods may be employed to produce a gel which may be readily filtered and washed,

metal ions be substantially removed by any .of a

number of alternative treatments. 'It is not known whether the alkali metal salts,-'such as sodium, are present in the primary hydrated composite in chemical combination or in an adsorbed state but it has been definitely determined that their removal is necessary if catalysts of superior value in accelerating the desired hydrocarbon reactions are to be obtained. It is possible that the presence of the alkali metal ions causes a sintering or fusion of the surfaces of washed with water and filtered to remove the major portion of soluble impurities. cipitate may then be removed from the filter or treated directly with relatively dilute hydrochloric acid and further carefully washed and freed from the major portion of adhering water.

As an alternative method or as an additional treatment for the removal of alkali metal which may be present in the chemically combined or adsorbed condition, the precipitated silica may be washed with solutions of ammonium chloride or other ammonium compounds which apparently serve to replace sodium by ammonium, any residual ammonium remaining in the hydrous silica aft-er subsequently water washing being readily volatilized in the drying and calcining oi the composited catalyst. The hydrous silica which is obtained as a filter cake may then be dried to form a dry mass with substantially all the water removed.

The aluminum in finely divided form may be added and distributed on the silica base subsequent to drying, or it may be added during the preparation of the hydrous silica. For example,

aluminum dust may be suspended and agitated in the sodium silicate solution while the acid is added, or the aluminum dust may be slurried with the precipitated hydrous silica as, for example, with 'the finally washed hydrous silica prior to drying. "'Although the dust or powdered form may be used when'depositing the aluminum on the silica, any other method of depositing the'aluminum may be used as, for example, by spraying with molten aluminum in the form of a mist. zWhen using the powdered aluminum, it

The premay be washed with a light petroleum distillate to free it from adhering grease, or it may be otherwise treated to insure its use in a substantially pure condition. Approximately 5 per cent, more or less, of the aluminum may be used with good results in accelerating the desired hydrocarbon conversion reactions, but I do not desire to limit myself to this proportion since much larger percentages of aluminum have been deposited upon the silica base with equally good results. It is not known to what extent the aluminum dust is modified or changed in the preparation and use of the present catalyst, but it may be possible that in the presence of air, moisture, and the active hydrous silica, the aluminum may be activated. or partly oxidized to some extent to form alumina. whatsoever the condition of the deposited aluminum, the activity of the silica is considerably promoted in accelerating the desired hydrocarbon reactions.

After the washing and drying treatment the catalyst may be powdered, consolidated, and sized in order to recover particles of a convenient granule size, or otherwise formed directly into pellets of the desired shapes by any type of press. It has been found that the apparently dry material has a total water content upwards of 15 per cent, but in the subsequent calcining treating at 850 to 900 and higher, dehydration occurs so that the water content is reduced to approximately 2 to 3 per cent which does not vary as a result of long service where a large number of reactivaiions with oxidizing gas are involved.

Catalysts prepared according to the above procedures evidently possess a large total contact surface corresponding to a high porosity, the pores being of such size that hydrocarbon vapors are" able to penetrate to a considerable distance and yet not so small that when the pores be- .come clogged with carbonaceous deposits after a long period of service they are diflicult to reactivate by'oxidation. This structure is also retained after many alternate periods of use and reactivation as evidenced by the fact that the catalysts may be repeatedly reactivated by passing air over the spent catalysts to burn ofl deposits of carbonaceous materials at temperatures as high as 1400 to 1600 F. without material 1053 of catalytic activity,

In accordance with the present invention, catalysts prepared by the general procedures described in the preceding paragraphs are conveniently utilized in cracking and reforming as filling material in tubes or chambers in the form of small pellets 0r granules. Although various sizes of granules may be used an average size which has proved useful is within the range of 6 to 10 mesh which may apply either to small pellets of uniform size and of short cylindrical shapes or to particles of irregular size and-shape produced by reducing the dried material to powdered condition, pressing to a cake,.reducing to desired meshes and returning fines for further pressing. While the simple method of preheating hydrocarbon oil vapors to a temperature suitable for their conversion or cracking in contact with the catalysts and then passing over the stationary mass of catalyst particles may be employed, it may be preferable to pass the preheated oil through banks of relatively small diameter catalyst-containing tubes in multiple connection between headers, since this arrangement of apparatus is better adapted to permit exterior heating of the catalyst tubes to compensate for the heat loss in the endothermic cracking reactions a 1d also permits the dissipation of the heat during the oxidation involved in regeneration treatment. After passage of the oil vapors through the catalysts the product is fractionated to separate the material which may be unsuitable for further cracking, intermediate insufliciently converted fractions which may be subjected to further catalytic cracking treatment, gasoline boiling range hydrocarbons, and gases, the intermediate fractions being returned directly to admixture with the charging stock so that ultimately there is complete recycling of intermediate insumciently converted material and a maximum utilization of the charging stock for gasoline production. Sufliciently converted products are directed to condensing, collecting, and stabilizing equipment where the gases" below the gasoline boiling point range are removed. Olefin hydrocarbons, r nore particularly propene and butenes which are present in higher yields than are usually obtained in other types of cracking, may be treated separately or the total gas may be flnally directed to polymerizing treatment by processes generally known in the art, either thermal or catalytic, to produce further yields of high antiknock gasoline. Y

The present process besides being characte ized by the use of novel catalysts is further characterized by the use of moderate temperatures, relatively low pressures, and short contact time; i. e., high throughput. In some cases the contact time and space velocity has been substantially varied without materially affecting the yield and character of the products. Temperatures employed in contact with the catalysts by flow conditions through the vaporizing and conversion zones and the subsequent fractionating and collecting equipment.

'The following specific example is given to illustrate the process of the invention, one method of preparing the catalyst also being given. The process should not be considered as limited to the example or to the particular catalyst preparation, these being given merely as illustrative of the novelty and utility of the invention.

The silica base for the catalyst was prepared by dissolving 415 grams of a commercial sodium silicate in 3 liters of water, and adding slowly 500 cc. of approximately 2.5 molar hydrochloric acid solution to bring about the precipitation of hydrous silica in an alkaline medium. The

hydrous silica was thus precipitated in a maner so as to produce a gel which could be handled-without dimculty in subsequent filtration and washing treatment. In the present case, after a preliminary wash with water to remove the major portion of the dissolved substances, a further wash with dilute acid and water was used, followed by a wash with dilute anmionium chloride solution. With a moderate amount of subsequent water wash the gel was rendered substantially free from harmful salts and was thereupon recovered as a filter cake. The filter cake was dried at approximately 230 F. and a relatively dry powder obtained. Five per cent by weight of aluminum dust which had 7 been previously washed with light petroleum distillate was thoroughly admixed with the substantially dry hydrous silica. The catalyst was then consolidated and granules of 6 to 10 mesh I formed which particles were then calcined at approximately 950 F. The invention should not be considered as limited to the present amount of deposited aluminum or the manner of preparation since any method'of spraying or depositing a metallic aluminum upon hydrous silica is considered within the scope of the invention.

A Pennsylvania gas-oil having an A. P. I. gravity of 37.3 was processed in a once-through operation, the oil being vaporized and preheated to a temperature of approximately 932 F at substantially atmospheric pressure and passed over the silica-aluminum catalyst above described, using a space velocity of 4, a flow rate which corresponds to relatively high capacity. The treated vapors were then condensed and an improved gasoline and highly oleflnic gas separated. The gasoline yield on the single pass was 21 per cent and it had an octane number using the Motor Method of '79. The by-product gas which corresponded to 6.2 per cent by weight of the-oil charged contained 66 weight per cent of propene and butenes, oleflns which upon polymerization in the presence of solid precalcined phosphoric acid catalyst at an elevated temperature yielded an additional 4.6 per cent of high antiknock polymer gasoline. The high proportion of olefins in the gas is especially emphasized since it appears to be specific to the present type of process, i. e., the olefins present in the gas are considerably higher in amount than is ordinarily experienced in strictly thermal cracking or. in catalytic processing where other types of catalysts, for example, dehydrogenation catalysts may be used.

I claim as my invention:

1. A process for converting hydrocarbon oils into substantial yields of motor fuel of high antiknock value, which comprises subjecting said oil at an elevated temperature above 500 F. to contact with a catalyst produced by precipitating a hydrous silica, washing and treating to substantially remove alkali metal ions, depositing metallic aluminum thereupon and drying, forming into granules and calcining.

2. A process for converting hydrocarbon oils into substantial yields of motor fuel of high antiknock value, which comprises subjecting said oil at a temperaturewithin the approximate range of 800-1200 F. and substantially atmospheric to moderately superatmospheric pressure to contact with a catalyst produced by precipitating and washing a hydrous silica, treating and washing to substantially remove alkali metal ions, drying, depositing metallic aluminum thereupon, forming into granules and calcining.

3. A process for converting hydrocarbon oils intosubstantial yields of motor fuel of high antiknock value, which comprises subjecting said oil at a temperature within the approximate range of 800-1200" F. and substantially- IVAR H. KINNEBERG. 

